The role should be supported, that is, the literal interpretation used for the shaft, but this is only part of its role, supporting its essence is to be able to assume radial load. It can also be understood that it is used to fix axes. Bearing fast and easy to choose automatic selection is included. That is, the fixed axis makes it possible to rotate only, and control its axial and radial movement. The motor cannot work without bearing. Because the shaft may move in any direction, the motor requires the shaft to rotate only when it is working. Theoretically impossible to achieve the role of transmission, not only that, bearing will also affect the transmission, in order to reduce the impact on the high-speed shaft bearings must achieve good lubrication, and some bearings themselves have been lubricated, called the pre-lubrication bearings, and most of the bearings must have lubricants, responsible for high-speed operation, Because friction will not only increase energy consumption, but also the more terrible is the easy damage to the bearing. The idea of turning a sliding friction into a rolling rub is one-sided, because there is something called a sliding bearing.